carefully REMOVE little useless antenna. use two soldering irons at the same time, to avoid pcb damage.
Scrape away the green solder resist as shown, add solder to it.
add new 2mm good quality coax cable, with SMA connector in the other end.
Enjoy full wifi range as any other usb dongle.
if you damage pcb, you can always just disable internal wifi, and use usb dongle wifi,
I just prefer the internal wifi since it require no fumble arround with hard to figure out settings.
